RE: Users named in Authors field getting error 4000 Stan Rogers 29.Aug.12 09:45 PM a Web browser Domino Designer 6.0.3Windows XP
Not necessarily, Mark -- you're looking at the saved document, and the user shouldn't be able to initiate the edit without being listed in a properly-flagged field. Since the save doesn't work, any value or flag changes can't be written to the saved document.
You'd need to pop the field flags and values during the action, just before the save is called, to see if there's a problem with either of them. There might be event code somewhere that's modifying the document in an unfortunate way before the action is triggered.